Design And Implemention Of A High-efficieney Power Amplifier Of Facing High Par Signals

Power amplifier has been widely used in radar, satellite, navigation and other mobile communication, and plays a key role in the wireless communication system. The continuous development of the modulation technology makes wireless communication standards such as 802.11, 4G etc. employing the high peak-to-average ratio (PAR) modulation signals.It is difficult to work highly efficiently in condition of high peak to average ratio for the traditional amplifier, which results in a huge waste of energy. Therefore, how to achieve a power amplifier realizing highly efficiently working for the high peak to average ratio signals has always been the hot research topic.This paper aims to improve the efficiency of power amplifier facing high peak to average ratio signals. To this end, this paper completed the following work:1) Through the analysis of the classical Doherty theory, focusing on the existing high back off power amplifier technology. This paper improves the traditional asymmetric Doherty power amplifier design method, and the optimized matching method is used to design the asymmetric Doherty power amplifier. The optimized design method not only ensures the high power back off region but also achieves high efficiency in the back off region. And this design method shortens the length of the power combined line, simplifies the Doherty circuit structure, reduces the circuit size.2) Through the theoretical analysis of the harmonic suppression class of power amplifier, the various parameters that need to be considered in the design of a continuous class F power amplifier are summarized.Based on the traditional model of the transistor offered by the refering papers, setting the output current and voltage waves in the current plane as the standards, design the corresponding matching circuit to maximize the efficiency in the whole frequency band.3) Designed and implemented a Doherty power amplifier working in 2.6GHz. The test results show that the asymmetric Doherty amplifier can achieve peak output power of 45dBm, during the back off region of 9.2dB more than 53% power added efficiency, and in the low power region, the performance of the power added efficiency greater than 55%also can be gotten. The 20MHz WCDMA modulation signal is used to test the linearity, when the output power is 35.8dBm, with the digital pre distortion technology, the optimal ACPR is less than -50dBc.4) Design a continuous F class power amplifier working in 1.8-2.7GHz. The simulated results show that the output power of 41 dBm is achieved in the whole frequency band, and 60%-75% power added efficiency also can be gotten.In this paper, the designed and implemented power amplifier qualifies good performance, which is of great practical value and application space. Especially for the asymmetrical Doherty power amplifier it has important reference value for the design and development of high efficiency and high back off power amplifier.